Reverse Shoulder Arthroplasty for B2 Glenoid Deformity

Abstract

In shoulder osteoarthritis, the B2 glenoid presents challenges in treatment because of the excessive retroversion and posterior deficiency of the glenoid. Correction of retroversion and maintenance of a stable joint line with well-fixed implants are essential for the successful treatment of this deformity with arthroplasty. Reverse shoulder arthroplasty offers several key advantages in achieving this goal, including favorable biomechanics, a well-fixed baseplate, and proven success in other applications. Techniques such as eccentric reaming, bone grafting, and baseplate augmentation allow surgeons to tailor treatment to the patient's altered anatomy. Eccentric reaming is favored for correction of small defects or mild version anomalies. Current trends favor bone grafting for larger corrections, though augmented components have shown early promise with the potential for expanded use. With overall promising results reported in the literature, reverse shoulder arthroplasty is a useful tool for treating older patients with B2 glenoid deformities.

Keywords: B2 glenoid; Reverse shoulder arthroplasty; baseplate augmentation; biconcave glenoid; eccentric glenoid reaming; glenoid bone grafting.

Figure 1.

A and B, Structural cortical bone grafting for posterior glenoid erosion can be accomplished by first creating a step cut in the glenoid surface with a bur. The graft can be fashioned from the humeral head and then placed in the defect. C and D, The humerus can then be prepared in standard fashion. E and F, After baseplate impaction, the peripheral locking screws in the baseplate provide fixation of the graft to the native glenoid.

Figure 2.

Impaction grafting can be done by morcellising the humeral head and packing it onto the posterior aspect of the baseplate (B). To optimize fixation, at least 50% of the baseplate should be supported on native bone, with the remainder supported through the bone graft (arrow). Postoperative radiographs demonstrate satisfactory healing of the graft (C and D).

Figure 3.

A patient with a B2 glenoid wear pattern treated with reverse total shoulder arthroplasty. A–C, The glenoid is asymmetrically reamed to prepare for an augmented baseplate . D and E, Postoperative radiographs show satisfactory correction with the augmented component (arrow).